How much the surcharge is
The nonmachinable surcharge is $0.49 on USPS's price list in effect since October 4, 2026, added to the regular letter price. With stamps, that makes these totals:
| Weight up to | Machinable letter | Nonmachinable letter |
|---|---|---|
| 1 oz | $0.82 | $1.31 |
| 2 oz | $1.11 | $1.60 |
| 3 oz | $1.40 | $1.89 |
| 3.5 oz | $1.69 | $2.18 |
What makes a letter nonmachinable
Section 101.1.2 of USPS's Domestic Mail Manual lists the characteristics. A letter size piece is nonmachinable if it has any one of them. Quoted as USPS writes them:
- "Has an aspect ratio (length divided by height) of less than 1.3 or more than 2.5."
- "Is polybagged, polywrapped, enclosed in any plastic material, or has an exterior surface made of a material that is not paper." Windows in paper envelopes are fine.
- "Has clasps, strings, buttons, or similar closure devices."
- "Contains items such as pens, pencils, keys, or coins that cause the thickness of the mailpiece to be uneven."
- It "is too rigid," which USPS defines as not bending easily around an 11 inch turn on a sorting belt pulled at 40 pounds of tension.
- It is thinner than 0.009 inch while being more than 6 inches long or 4 1/4 inches high.
- "Has a delivery address parallel to the shorter dimension of the mailpiece."
- It is a self mailer or a booklet that isn't folded and sealed the way USPS requires.
The aspect ratio rule is why square greeting cards cost more. A #10 envelope is 9 1/2 by 4 1/8 inches, a ratio of 2.3, and a #6 3/4 envelope is 1.79, so both pass.
Is a toploader nonmachinable?
Not by itself. A single standard toploader in a #10 envelope still lets the envelope bend, and most card sellers mail them that way as regular letters for one Forever stamp. What pushes a card mailer over the line is stiffness: a toploader taped to a piece of cardboard, two toploaders stacked on top of each other, a thick magnetic holder or a graded slab. Sorting machines bend each letter around belts, and USPS's rigidity test is whether it bends around an 11 inch turn.
Clerks at the counter decide by hand, and some will charge the surcharge on any toploader mailer. If you want to be sure, flex the sealed envelope: if it bends easily along its length, it should pass. The letter checker runs every rule above on your mailer's size, thickness and weight.
The nonmachinable stamp
USPS issues stamps for letters that owe the surcharge, usually sold with square greeting cards in mind. A stamp like that covers a 1 ounce nonmachinable letter at the price it was issued for. You don't need a special stamp, though. Any stamps that add up to the right amount pay for the letter, so a Forever stamp plus 49 cents in other stamps does the same job.
A letter with too little postage can be sent back to you or delivered with postage due, which means your buyer pays it. Mana Pool's help center warns sellers that repeated short postage can get a seller account disabled.
Why nonmachinable letters lose their scans
A USPS Intelligent Mail barcode is read by the same machines that sort the letter. A nonmachinable letter skips those machines and is sorted by hand, so it usually gets a scan or two at most, and often none, even though it is moving normally. If your tracked letters keep showing "in the mail" and nothing more, check whether they're nonmachinable before blaming the barcode.
Some letters lose scans for another reason. USPS's own table of delivery areas marks about 17% of ZIP codes as zones where mail is sorted by hand at the last step and "no tracking code scans should be generated." Those letters still get the plant scans on the way.
How to keep a card mailer machinable
- Use a rectangular paper envelope, a #10 or a #6 3/4, with the address along the long side.
- Use one toploader, or two side by side, never stacked, and no cardboard taped around them. Mana Pool suggests double sided tape to keep two team bags from overlapping.
- Keep it flat and even: no coins, pins or loose items, and no thick lump in one corner.
- Keep the outside paper. A team bag inside is fine; a poly mailer outside is not.
- If the order won't fit those limits, send it as a package with a label rather than paying the surcharge on a letter that will lose its scans.
Questions
How much is the nonmachinable surcharge?
$0.49, on USPS's prices in effect since October 4, 2026. A 1 ounce nonmachinable letter costs $1.31 with stamps.
What qualifies as nonmachinable?
A letter that is square or very long for its height, plastic on the outside, closed with a clasp or string, lumpy, too stiff to bend, very thin for its size, or addressed along the short side.
Is a toploader nonmachinable?
One toploader in a #10 envelope usually is not, because the envelope still bends. Taped to cardboard, stacked or in a rigid holder, it is.
What is the nonmachinable stamp?
A stamp USPS issues to cover a 1 ounce nonmachinable letter, often sold for square greeting cards. A Forever stamp plus 49 cents in other stamps pays the same postage.
Why do my nonmachinable letters lose scans?
They are sorted by hand instead of by the machines that read the barcode, so few scans or none are recorded.
Sources
- USPS, Notice 123 price list, effective October 4, 2026: pe.usps.com/text/dmm300/Notice123.htm
- USPS, Domestic Mail Manual 101, physical standards for letters and flats, read October 19, 2026: pe.usps.com/text/dmm300/101.htm
- USPS, Automated Zone Indicator table, file of September 5, 2026: postalpro.usps.com. The 17% share is our count of the ZIP codes in that file.
- Mana Pool, "Make sure to use the correct postage for USPS First Class (Letter) packages that are over 1oz" and "Tips on avoiding delivery issues with shipments", updated September 20, 2026: support.manapool.com